Pressure adjusting device



Nov. 29, 1938. P. DIETRICH 2,138,142

PRESSURE ADJUSTING DEVICE Filed April 17, 19:57

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f www Patented Nov. 29, 1938 UNITED STATES PATENT oFF-ica 2,133.14:v PRESSURE ADJUs'rlNG nevica' Application April 17, 1937, Serial No.. y187,133 In Germany October .26, 1935 2Claims.

In rotary photogravure machines the'web to be printed passes between two cylinders which are pressed against each other and of which one, the impression cylinder, to adjust the degree of pressure is moved towards the other cylinder, the form cylinder, or away therefrom. It has hitherto been impossible to adjust the degree of pressure accurately enough or, after, a temporary alteration thereof to restore the earlier condition l0. because the mechanical means applied to this end lacked precision and were too complicated and unreliable in their action. Accurate adjustment is however indispensable, for instance in multil color printing, because proper register of the several succeeding impressions can be obtained l only if the tension of the web be kept even, and the tension varies withthe degree of pressure between the cylinders. If in machines equipped with any of the known adjusting devices the web U during the run accidentally breaks, the machine is liable to get unduly strained and damaged through the rear end of the broken web getting wound around one of the cylinders or an intermediary roll disposed between the two cylinders.

25 The object of the invention is a pressure adjusting device o! high precision which'has none of these drawbacks. 1

According to the invention the impression cylinder consists of a rotatable jacket on an eccen- 80 trically journalled core, which core it rocked one -way or the other will either bring the impression cylinder nearer to, or remove it further away from the form cylinder, thereby adjustingthe degree.

of pressure. The rocking motion is eiected by 85 means of two pneumatic cylinders, one each for eiIecting either movement.

Fig. 1 of the drawing is a side view of a preferred form of the device according to the invention; 40 Fig. 2 a longitudinal section thereof.

The printing mechanism comprises a. form `c`ylinder l, an intermediary roll 2 and an'im- ,pression cylinder, the jacket 3 of which rotates on the core 4 oi the cylinder.

` the intermediary roll 2 are carried by a slidable frame 6 which. by means of a screw spindle 'l4 and a wormgear 9, N in the maimframe of. the

- The eccentrically` A45 to the jacket 3 located journal 5 of the core 4 and (Cl. lill-247) against one of diil'erent diameter. Rigidly 'connected with the journal I is a two-arm lever Il which by means ofthe two piston rods l2 and I3 of the pneumatic cylinders II and l5 maybe turned one way or the other. The action of the l pneumatic cylinders is controlled by two threeway cocks I6 and I1 which at will establish communication either with the delivery pipe or the outer air. Pressure is regulated by means oi a reduction valve I. .1

In place of the two single-actinghpistons I4 and I5 one double-acting piston maybe used.

- Thetwo three-way cocks I6 and I'l may also be replaced by one double-acting one. v

As represented in lthe drawing the impression l5 cylinder 3 will be brought closer to the form cylinder if the piston I4 moves to the right, and removed therefrom if the piston I5 is moved to the right. Since the intermediary roll 2 is pressed against the impression cylinder by a spring 20, also disposed within the slidable frame 6, it will follow its every movement.

Instead of the pneumatic cylinders, other means such as hydraulic, mechanical or electrical means 'may be used to act on the lever Il inthe manner 25 described. The pneuniaticallyA actuated adjustment device has however the advantage of being elastic, thereby preventing'undue strain on any of' the separate parts of the printing mechanism incase o1 breakage of the web and consequent $0 troubles.

Having now particularly describedyand ascer\ tained the nature ot my said invention and in` what manner the same is to be performed, I declare what I claim is: l'

1. In a rotary printing press, in combination with the form cylinder, a. cylindrical core rotatably supporting an impression cylinder and having journals eccentric relative to said impression cylinder, bearings for said journals, a two-arm 40 lever attached to one of said journals. and means connected to -the arms of said lever for pivoting the same in either direction for turning said core to thereby adjust the position of said ini-pression cylinder relative to said form cylinder.

2. The combination as specied in claim 1, in which said means for pivoting said lever comprises two pneumatic cylinders, movable pistons in said printing machine may be moved vertically within 50 wide limits torrough adjustment, or when exchangingia form cylinder of a certain diameter cylinders, and piston rods connecting saidpistons y with the arms of said twoarm lever.

' PAUL DIETRICH. 

